Ascii data with date and time in the file

[Ben Burford <benb@xxxxxxxxxxxx>]

Hello All,

I'm new to Ferret and I have some slightly complicated data to work with.  I
 have station data in ascii where the date and time (year, month, day, hour,
 minute) for each set of readings is in the file.  The date/time and data ar
e recorded at a 30 minute interval.  However, one of the most important feat
ures of this data is that the time series is not continuous - the instrument
 may drop out and back in randomly.  So, there may be one, or any number of 
times missing in the date/time sequence.  

For simplicity I will focus on one variable (air_temperature).  The data in 
the file looks like this:

2002/10/01 00:30, -0.1
2002/10/01 01:00, 0.98
2002/10/01 01:30, 2.66
2002/10/01 02:00, 4.12
2002/10/01 02:30, 6.23
etc.


Information about the data from the DODS server:

date_year, date_month, date_day, date_hour, date_min, . . . air_temperature,
 . . . 

Int32 date_year;
Int32 date_month;
Int32 date_day;
Int32 date_hour;
Int32 date_min;
Float32 air_temperature;


One of the nice features of the server is that there are functions to allow 
me various ways to access the date/time information:

1. Separate - year, month, day, hour, minute values:

2002, 10, 1, 0, 30,
2002, 10, 1, 1, 0,
2002, 10, 1, 1, 30,
2002, 10, 1, 2, 0,
2002, 10, 1, 2, 30,
etc.


2. A date/time string

"2002/10/1:00:30:00 GMT"
"2002/10/1:01:00:00 GMT"
"2002/10/1:01:30:00 GMT"
"2002/10/1:02:00:00 GMT"
"2002/10/1:02:30:00 GMT"
etc.


3. A decimal year where the date and time are used to calculate a floating-p
oint "fractional year":

"2002.7480022831"
"2002.7480593607"
"2002.7481164384"
"2002.748173516"
"2003.2437214612"
"2003.2437785388"
"2003.2438356164"


So, can you tell me how to plot this data with Ferret (knowing that the date
/time is not continuous) plotting air_temperature against time?

Thank you,

Ben